The objectives of this study are to measure Impulse Oscillometry (IOS) in patients with
asthma extensively at baseline in patients with mild-to-moderate asthma, treated with
as-needed short acting beta agonist only, to measure respiratory resistance and small airway
dysfunction accurately and precisely at baseline, from which to measure onset of action of
Advair MDI in comparison with that of Symbicort MDI. Initial screening will assess IOS
resistance and small airway dysfunction and its response to short acting beta agonist
(SABA). Patients will be selected from among those who manifest a 40% improvement in small
airway function assessed by IOS low frequency reactance after SABA compared to baseline.
After screening, patients will be randomized to receive either Advair or Symbicort; and will
be assessed at randomization before and at several intervals after initial dosing, up to 4
hours. Patients will return again 4 weeks after randomization for extended IOS (and
spirometry) testing as done at randomization.

Clinical Details

Official title: Onset of Action of Advair HFA 115/21 in Comparison to Symbicort pMDI 160/4.5 Measured by Impulse Oscillometry, IOS.

Model-derived estimates of Large and Small Airway Resistance and Compliance, and their changes after initial dosing

Detailed description:
Eligibility criteria include age 12-45 years, with current treatment of asthma with
as-needed SABA only; and manifesting an acute response to SABA at screening of 40% or
greater improvement in IOS low frequency reactance. After inclusion in the protocol, all
subjects will receive active treatment, either with Advair or with Symbicort. Outcome
measures will include large and small airway resistance and integrated low-frequency
reactance calculated directly from IOS measures, and in addition, Large Airway Resistance,
Small Airway Resistance and Small Airway Compliance derived from an electrical equivalent
respiratory system model. Analysis of IOS data will be done post-testing by a respiratory
physiologist, experienced with use of IOS and its analysis and interpretation, blinded to
which treatment each individual received. Electrical-equivalent respiratory system model
analyses will be done by a biomedical engineer, blinded to which treatment each individual
received.